---
layout: docs
page_title: Domain Model - Host Sets
description: |-
  The anatomy of a Boundary host set
---

# Host Sets

A host set is a resource
that represents a collection of [hosts][]
which are considered equivalent
for the purposes of access control.
A host set can only include hosts
from the same [host catalog][] as the host set.
A [target][] can reference host sets from host catalogs
which belong to the same [project][] as the target.

## Attributes

A host set has the following configurable attributes:

- `name` - (optional)
  If set, the `name` must be unique within the host set's parent [host catalog][].

- `description` - (optional)

- `preferred_endpoints` - (optional)
  A list of selector strings in the format of either `cidr:<valid IPv4/6 CIDR>`
  or `dns:<globbed name>` used to select the addresses of [hosts][] when
  establishing a [session][] with a [target][].

### Plugin Host Set Attributes

- `attributes` - (optional)
  A collection of fields which the plugin uses to lookup which hosts should be
  members of this host set.  Often this includes a type of filter using a
  syntax which is usable by the backing service.

- `sync_interval_seconds` - (optional)
  The number of seconds between the time boundary syncs the [hosts][] in this
  set using this host set's plugin. If not provided a system determined default
  is used.

## Referenced By

- [Host][]
- [Host Catalog][]
- [Target][]

[host catalog]: /boundary/docs/concepts/domain-model/host-catalogs
[host catalogs]: /boundary/docs/concepts/domain-model/host-catalogs
[host]: /boundary/docs/concepts/domain-model/hosts
[hosts]: /boundary/docs/concepts/domain-model/hosts
[project]: /boundary/docs/concepts/domain-model/scopes#projects
[projects]: /boundary/docs/concepts/domain-model/scopes#projects
[session]: /boundary/docs/concepts/domain-model/sessions
[sessions]: /boundary/docs/concepts/domain-model/sessions
[target]: /boundary/docs/concepts/domain-model/targets
[targets]: /boundary/docs/concepts/domain-model/targets

## Service API Docs

The following services are relevant to this resource:

- [Host Set Service](/boundary/api-docs/host-set-service)
